As exemplified by the optical fiber cleaving tool of Thomas and Betts Corporation of Raritan, New Jersey, termination tool model DW9000, of the Deutsch Optical Waveguide, the fiber breaking machine Model CS-2 of Custom Scientific Instruments, Inc., Whippany, N.J. and the splicing instrument for optical fibers and cable of Sumitomo Electric Ind. of Tokyo, Japan various systems for the cleaving or separation of optical fibers have been provided in which the fibers are held stationary, with one or more parts being moved into contact with the fiber to effect a scribe and break-type operation.
As described in a paper entitled, Optical Fiber End Preparation for Low-Loss Splices, by D. Gloge et al, Bell System Technical Journal, vol. 52, pp. 1579-1588, conventional grinding and polishing techniques turn out to be time consuming and costly when trying to provide simple and inexpensive splicing techniques for cables made from brittle materials like glass. As described in this article, it is the purpose of these techniques to provide flat and perpendicular end faces for the fibers. It is thus necessary to provide absolute control of the breaking process in order to obtain utmost reliability for splices made by scoring and then breaking the optical fiber. While the above-mentioned tools have provided for the cleaving of optical fibers, in general these devices have involved multiple parts which are moved to the fiber in order to provide for the scribing and breaking functions.
It should be noted that it has been well documented that glass rods tend to break in such a way that the fracture face comprises three regions known as the mirror, the mist, and the hackle zones. The mirror zone is an optically smooth surface adjacent of the fracture origin, the hackle zone corresponds to an area where the fracture has forked and the specimen is separated into three or more pieces, and the mist zone is a transition region between these two zones. As will be appreciated, the hackle zone may be manifested in the form of a lip or a breakaway to the side of the fiber opposite the scribed portion.
It is the purpose of any optical fiber splicing tool to provide a cleaved fiber in which the cleavage plane is perpendicular to the longitudinal axis of the fiber and in which the surface is optically flat or mirrored. Improperly cleaved fibers will either have an oblique cleavage plane or will have either a lip or a breakaway at the side of the fiber opposite the scribe point.
As is conventional, fibers are provided with a cladding layer and it is the cladding layer which is usually scribed as opposed to the inner core or fiber. While lips or breakaways of the cladding layer present little difficulty in terms of transmission characteristics, if the lip or breakway extends into the core, significant transmission losses occur. Moreover, in the case of a lip, the presence of a lip prevents close spacing of end-to-end mated fibers which affects transmission between coupled fibers.